Add README.md with install/run instructions

tools/lsp/README.md

@@ -0,0 +1,27 @@
+
+To compile and run, the following tools are needed:
+
+1) tree-sitter-clr (the Node.js one was usied during development)
+2) optionally, nix package manager
+3) haskell-stack
+
+First, you need to generate the `parser.c`.
+For that, do
+
+```
+cd tools/lsp/pascaligo
+tree-sitter generate
+```
+
+Then
+```
+cd ../squirrel
+stack install
+```
+
+To use the executable, do
+```
+squirrel <filename>.ligo
+```
+
+At this stage of development, it first prints the dump of tree-sitter parse tree, then its attempts to build actual parse tree.